[C/C++] 快速求 sqrt 倒數的方法
float InvSqrt (float x) { float xhalf = 0.5f*x; int i = *(int*)&x; i = 0x5f3759df – (i>>1); x = *(float*)&i; x = x*(1.5f – xhalf*x*x); return x;} …
difference
float InvSqrt (float x) { float xhalf = 0.5f*x; int i = *(int*)&x; i = 0x5f3759df – (i>>1); x = *(float*)&i; x = x*(1.5f – xhalf*x*x); return x;} …